Kenneth Walter Rosenberg (born July 9, 1995) is an American professional

baseball Baseball is a bat-and-ball games, bat-and-ball sport played between two team sport, teams of nine players each, taking turns batting (baseball), batting and Fielding (baseball), fielding. The game occurs over the course of several Pitch ...

pitcher In baseball, the pitcher is the player who throws ("Pitch (baseball), pitches") the Baseball (ball), baseball from the pitcher's mound toward the catcher to begin each play, with the goal of out (baseball), retiring a batter (baseball), batter, ...

for the

Kiwoom Heroes The Kiwoom Heroes () are a South Korean professional baseball, professional baseball team based in Seoul. They are a member of the KBO League. The Heroes play their home games at Gocheok Sky Dome in Gocheok-dong, a neighborhood located in the sou ...

of the

KBO League The KBO League () is a professional baseball league in South Korea. The league comprises ten teams. The KBO League was founded with six franchises in 1982 and is the most popular sports league in South Korea. The Kia Tigers are the most success ...

. He has previously played in

Major League Baseball Major League Baseball (MLB) is a professional baseball league composed of 30 teams, divided equally between the National League (baseball), National League (NL) and the American League (AL), with 29 in the United States and 1 in Canada. MLB i ...

(MLB) for the

Los Angeles Angels The Los Angeles Angels are an American professional baseball team based in the Greater Los Angeles, Greater Los Angeles area. The Angels compete in Major League Baseball (MLB) as a member club of the American League (AL) American League West, ...

. He played

college baseball College baseball is baseball that is played by Student athlete, student-athletes at institutions of higher education. In the United States, college baseball is sanctioned mainly by the National Collegiate Athletic Association (NCAA); in Japan, ...

California State University, Northridge California State University, Northridge (CSUN or Cal State Northridge), is a public university in the Northridge neighborhood of Los Angeles, California, United States. With a total enrollment of 36,848 students (as of Fall 2024), it has the ...

, and was drafted by the

Tampa Bay Rays The Tampa Bay Rays are an American professional baseball team based in the Tampa Bay area. The Rays compete in Major League Baseball (MLB) as a member club of the American League (AL) American League East, East Division. They are one of two major ...

in the 8th round of the

2016 MLB draft The 2016 Major League Baseball draft began on June 9, 2016, to assign amateur baseball players to MLB teams. The draft order is the reverse order of the 2015 MLB season standings. In addition, compensation picks were distributed for players who ...

. He made his MLB debut with the Angels in 2022.

Amateur career

Rosenberg was born in

Mill Valley, California Mill Valley is a city in Marin County, California, United States, located about north of San Francisco via the Golden Gate Bridge and from Napa Valley. The population was 14,231 at the 2020 United States census, 2020 census. Mill Valley is lo ...

, a small town north of San Francisco, later lived in

Santa Clarita, California Santa Clarita (; Spanish for "Little St. Clare") is a city in northwestern Los Angeles County, California, United States. With a 2020 census population of 228,673, it is the third-most populous city in Los Angeles County, the 17th-most popul ...

, and is Jewish. He attended

Tamalpais High School Tamalpais High School (often abbreviated as Tam) is a public secondary school located in Mill Valley, California, in the San Francisco Bay Area. It is named after nearby Mount Tamalpais, which rises almost above Mill Valley. Tamalpais High Scho ...

, where he was an All-

MCAL The North Coast Section (NCS) is a part of the California Interscholastic Federation, governing the eastern portion of the San Francisco Bay Area, up along the northern coast of the state of California, from Fremont in the south to Crescent ...

First Team

and

first baseman A first baseman, abbreviated 1B, is the player on a baseball or softball team who fields the area nearest first base, the first of four bases a baserunner must touch in succession to score a run. The first baseman is responsible for the majori ...

in baseball in 2013, as well as an All-League goalkeeper in soccer. As a senior, on the mound Rosenberg had 75

strikeout In baseball or softball, a strikeout (or strike-out) occurs when a batter accumulates three strikes during a time at bat. It means the batter is out, unless the third strike is not caught by the catcher and the batter reaches first base safe ...

s in 49

inning In baseball, softball, and similar games, an inning is the basic unit of play, consisting of two halves or frames, the "top" (first half) and the "bottom" (second half). In each half, one team bats until three outs are made, with the other tea ...

s, with two

shutout In team sports, a shutout (North American English, US) or clean sheet (Commonwealth English, UK) is a game in which the losing team fails to score. While possible in most major sports, they are highly improbable in some sports, such as basketba ...

s. He then attended

, majoring in journalism. In his sophomore season in 2016, he posted a 6–1 record with a 3.21

earned run average In baseball statistics, earned run average (ERA) is the average of earned runs allowed by a pitcher per nine innings pitched (i.e. the traditional length of a game). It is determined by dividing the number of earned runs allowed by the number ...

(ERA) and led the

Big West Conference The Big West Conference (BWC) is an American collegiate List of NCAA conferences, athletic conference whose member institutions participate in the National Collegiate Athletic Association's NCAA Division I, Division I. The conference was origina ...

with 118 strikeouts (in 109 innings), ahead of eventual

Cy Young Award The Cy Young Award is given annually to the best pitchers in Major League Baseball (MLB), one each for the American League (AL) and National League (baseball), National League (NL). The award was introduced in 1956 by Commissioner of Baseball ( ...

winner

Shane Bieber Shane Robert Bieber (born May 31, 1995) is an American professional baseball pitcher for the Cleveland Guardians of Major League Baseball (MLB). As a walk-on, Bieber played college baseball for the UC Santa Barbara Gauchos, and was selected by ...

, as he held batters to a .198 batting average. He was named Big West Conference All-Academic Team.

Professional career

Tampa Bay Rays

Rosenberg was drafted by the

in the 8th round of the

2016 Major League Baseball draft The 2016 Major League Baseball draft began on June 9, 2016, to assign amateur baseball players to MLB teams. The draft order is the reverse order of the 2015 MLB season standings. In addition, compensation picks were distributed for players who ...

. In 2016, between the rookie-level Gulf Coast League Rays and

Princeton Rays The Princeton Rays were a Minor League Baseball team in Princeton, West Virginia, operating as an Advanced Rookie-level team in the Appalachian League. The team was affiliated with several Major League Baseball (MLB) franchises, primarily the Ta ...

, he went 1–2 with a 2.54 ERA, with 33 strikeouts in innings. In 2017, Rosenberg pitched for the Single–A

Bowling Green Hot Rods The Bowling Green Hot Rods are a Minor League Baseball team of the South Atlantic League and the High-A affiliate of the Tampa Bay Rays. They are located in Bowling Green, Kentucky, and play their home games at Bowling Green Ballpark, which ...

. He went 7-7 with one save and a 4.28 ERA, and his 133 strikeouts ranked third in the

Midwest League The Midwest League is a Minor League Baseball league established in 1947 and based in the Midwestern United States. A Class A league for most of its history, the league was promoted to High-A as part of Major League Baseball's 2021 reorganizat ...

and fourth in the Rays organization, as he had 10.5 strikeouts per 9 innings. In 2018, Rosenberg pitched for the

Charlotte Stone Crabs The Charlotte Stone Crabs were a Minor League Baseball team located in Port Charlotte, Florida, from 2009 to 2020. They competed in the Florida State League (FSL) as the Class A-Advanced affiliate of the Tampa Bay Rays Major League Baseball (MLB) ...

of the Single–A

Florida State League The Florida State League (FSL) is a Minor League Baseball league based in the state of Florida. Having been classified at various levels throughout its existence, it operated at Class A-Advanced from 1990 until its demotion to Single-A following ...

. He went 11-2 with a 4.86 ERA, as his 11 wins ranked third in the league, his 106 strikeouts were sixth, and his .846

winning percentage In sports, a winning percentage or Copeland score is the fraction of games or matches a team or individual has won. The statistic is commonly used in standings or rankings to compare teams or individuals. It is defined as wins divided by the to ...

was eighth. In 2019, Rosenberg pitched primarily for the Double-A

Montgomery Biscuits The Montgomery Biscuits are a Minor League Baseball team based in Montgomery, Alabama. They are the Double-A affiliate of the Tampa Bay Rays and play in the Southern League. The team was founded in Orlando, Florida, in 1973 as the Orlando Twins ...

, also pitching in one game for the Triple-A

Durham Bulls The Durham Bulls are a Minor League Baseball team of the International League and the Triple-A affiliate of the Tampa Bay Rays. They are located in Durham, North Carolina, and play their home games at Durham Bulls Athletic Park, which opened ...

. He went 11-4 with a 3.29 ERA in 25 games (16 starts) for Montgomery, and was named a midseason Southern League All Star. He tied for the league lead in wins, ranked fourth in ERA, and ninth in strikeouts with 108. His aggregate 114 strikeouts were third among Rays minor leaguers. Rosenberg did not play in a game in 2020 due to the cancellation of the minor league season because of the

COVID-19 pandemic The COVID-19 pandemic (also known as the coronavirus pandemic and COVID pandemic), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), began with an disease outbreak, outbreak of COVID-19 in Wuhan, China, in December ...

. The Rays invited Rosenberg to

spring training Spring training, also called spring camp, is the preseason of the Summer Professional Baseball Leagues, such as Major League Baseball (MLB), and it is a series of practices and exhibition games preceding the start of the regular season. Spri ...

in 2021. He split the 2021 season between the FCL Rays, Montgomery, and Durham, going a combined 4-1 with a 2.81 ERA and 59 strikeouts over innings (12.7 strikeouts per 9 innings).

Los Angeles Angels

2022

On December 8, 2021, Rosenberg was selected by the

with the 8th pick in the minor league phase of the 2021

Rule 5 draft The Rule 5 draft is a Major League Baseball (MLB) player draft that occurs each year in December, at the annual Winter Meeting of general managers. The Rule 5 draft aims to prevent teams from stockpiling too many young players on their minor lea ...

. Rosenberg opened the 2022 season with the

Salt Lake Bees The Salt Lake Bees are a Minor League Baseball (MiLB) team that plays in the Pacific Coast League (PCL) and are the Triple-A affiliate of the Los Angeles Angels. Based in South Jordan, Utah, the team plays its home games at The Ballpark at Am ...

. On April 18, 2022, the Angels selected his contract and promoted him to the major leagues for the first time. He made his MLB debut that day, surrendering a run in relief against the

Houston Astros The Houston Astros are an American professional baseball team based in Houston. The Astros compete in Major League Baseball (MLB) as a member club of the American League (AL) American League West, West Division. They are one of two major leag ...

while striking out two. The following day, the Angels optioned Rosenberg back to Salt Lake. Rosenberg was recalled by the Angels on May 31 and made his second career major league appearance that day, throwing 99 pitches in 5 innings of relief against the

New York Yankees The New York Yankees are an American professional baseball team based in the Boroughs of New York City, New York City borough of the Bronx. The Yankees compete in Major League Baseball (MLB) as a member club of the American League (AL) Am ...

. On June 19, Rosenberg made his first career start, pitching scoreless innings against the

Seattle Mariners The Seattle Mariners are an American professional baseball team based in Seattle. The Mariners compete in Major League Baseball (MLB) as a member club of the American League (AL) American League West, West Division. The team joined the American ...

. In 2022 with the Salt Lake Bees, he was 2-5 with a 3.16 ERA (tied for 9th in the PCL) in 14 games (13 starts) covering innings in which he struck out 60 batters. On December 12, 2022, Rosenberg was

designated for assignment Designated for assignment (DFA) is a contractual term used in Major League Baseball (MLB). A player who is designated for assignment is immediately removed from the team's 40-man roster, after which the team must, within seven days, return the pla ...

following the signing of Justin Garza. He cleared waivers and was sent outright to Salt Lake on December 19.

2023

In 20 starts for Triple–A Salt Lake in 2023, he posted a 7–7 record and 4.95 ERA with 120 strikeouts (6th in the

Pacific Coast League The Pacific Coast League (PCL) is a Minor League Baseball league that operates in the Western United States. Along with the International League, it is one of two leagues playing at the Triple-A (baseball), Triple-A level, which is one grade bel ...

) in 100 innings of work (10.8 strikeouts per 9 innings; leading all pitchers who pitched 80 or more innings). On August 5, 2023, the Angels selected Rosenberg's contract, adding him to the major league roster. With the Angels in 2023, Rosenberg was 2-2 with a 3.82 ERA, as in 33 innings he struck out 29 batters. He mostly threw a 91 mph four-seam fastball and an 82 mph change-up, along with an 83 mph slider and a 77 mph curveball.

2024

Rosenberg was optioned to Triple–A Salt Lake to begin the 2024 season. With Salt Lake, he was 9-7 with a 4.21 ERA in 21 starts (one complete game; tying for league lead) covering innings. His nine wins tied for fourth in the league. With the Angels he was 0-1 with a 6.00 ERA in seven games (one start) in which he pitched 24 innings. He was released on November 4, 2024.

Kiwoom Heroes

On November 25, 2024, Rosenberg signed an $800,000 contract with the